GB800394A - Land vehicular gas turbine control system - Google Patents

Abstract

800,394. Gas turbine plant. MANNING, MAXWELL, MOORE, Inc. July 11, 1956 [July 22, 1955], No. 21492/56. Class 110 (3). [Also in Group XXIX] A gas turbine plant for a vehicle comprising a compressor system feeding air to combustion equipment supplying a turbine system driving the compressor system and the vehicle propelling means, has the fuel supply to the combustion equipment controlled by means for varying the area of a metering valve in accordance with variations in the compressor system output pressure up to a predetermined maximum value and manually operable means for adjusting the maximum value. The invention is described with reference to a gas turbine plant comprising a compressor supplying air to a combustion chamber through an exhaust gas heat exchanger. The combustion gases are supplied to two turbines arranged in series, the highpressure turbine driving the compressor and the low-pressure turbine the road wheels through reduction gearing. Fuel from a pump driven by the compressor-turbine shaft is fed to a fuel metering unit 42a, Fig. 2, through a conduit 44. The fuel then passes through a metering orifice 88 controlled by a metering valve 86 to a pressure regulator and fuel shut-off unit 43 connected to the fuel injector manifold by a conduit 48. The pressure regulator 43 comprises a spring-loaded valve 90 attached to a diaphragm 91 so as to maintain a constant pressure drop across the metering valve 86 despite variations in fuel pump or manifold pressure. The valve 86 is connected to the hub member 75 of a flexible diaphragm 71 enclosed in a housing 70. The chamber 72 on one side of the diaphragm 71 is vented to atmosphere through the outlet 73. The chamber 96 on the other side of the diaphragm 71 is connected to the compressor discharge through a pressure-reducing orifice 95 and a conduit 46. A slide valve 78 journalled in the end wall of the housing 70 is adapted to slide in the bore 76 of the member 75 to control the opening of an orifice 79. The slide valve is spring loaded leftwards and may be operated by the accelerator pedal acting through the lever 56. When the plant is stopped, the slide valve 78 closes the orifice 79 and diaphragm 71 is urged by the spring 85 against an adjustable starting fuel stud 84. When the ignition switch is closed and starter motor energized, fuel is supplied to the burners through the minimum fuel flow setting of the metering valve 86. As the speed of the turbine increases, the compressor delivery pressure increases and moves the diaphragm 71 away from the stud 84 thereby increasing the fuel supply and causing a further increase in turbine speed. This acceleration continues until the diaphragm 71 has moved far enough to cause the orifice 79 to be opened: The chamber 96 is then vented to atmosphere through the bore 76, outlet 77 and outlet 73 so that further movement of the diaphragm 71 and opening of the metering valve 84 is prevented. An adjustable stop 81 limits the leftward movement of the slide valve 78 and accordingly adjusts the correct fuel flow for idling conditions. If the accelerator pedal is now depressed, the slide valve 78 is moved to the right and the orifice 79 closed. The pressure in chamber 96 then builds up and the diaphragm 71 opens the metering valve 86 still further until the orifice 79 is re-opened. To limit the temperature of the turbine exahust gases or the temperature at any other point in the system, a unit 51 comprising a normally closed bleed orifice 100 controlled by a baffle 101 is provided. Upon the predetermined temperature being exceeded the orifice 100 is opened so that chamber 96 is vented to atmosphere and the fuel supply thereby reduced. A simple speed control 50 for the compressor driving turbine comprises bellows 111, 112 connected respectively to the atmosphere and the compressor discharge. When the compressor pressure ratio exceeds a predetermined value, the valve 116 is opened and the chamber 96 vented to atmosphere. An orifice 115 and adjustable orifice 115a permit precise adjustment of the desired pressure ratio at which the control operates. The Specification also describes in detail practical constructions of the controls 42, 43 and 50. The control 43 has an electrically operated shut-off valve combined with it. Specification 785,949 is referred to.